Lactose Intolerance

Lactose intolerance is the inability to digest significant amounts of lactose, the major sugar found in milk.

What causes lactose intolerance?
Lactose intolerance results from a shortage of the enzyme lactase. Lactase breaks down milk sugar into simpler forms that can be absorbed into the blood stream. When there is not enough lactase to digest the amount of lactose consumed, the results are usually not dangerous, but symptoms of lactose intolerance can be uncomfortable.

What are the signs and symptoms of lactose intolerance?
Common symptoms of lactose intolerance may include nausea, cramps, bloating, gas, and diarrhea. Symptoms typically begin about 30 minutes to 2 hours after eating or drinking foods containing lactose. The severity of symptoms depends on many factors, including the amount of lactose a person can tolerate and a person’s age, ethnicity, and digestion rate.

How is lactose intolerance diagnosed?
The most common tests used to measure the absorption of lactose in the digestive system are the lactose tolerance, hydrogen breath, and stool acidity tests.
The Lactose Tolerance Test. You’ll need to avoid eating before this test to ensure accurate results. Several blood samples are taken over a 2-hour period to measure your blood glucose (blood sugar) level. This test will indicate how well the body is able to digest lactose.
The Hydrogen Breath Test. This test measures the level of a gas called hydrogen in your breath. Hydrogen is produced by bacteria in the colon (large intestine) in response to undigested lactose. Hydrogen is carried through the blood stream to the lungs, where it is breathed out. High levels of hydrogen in your breath means that lactose is not being digested properly.
Stool Acidity Test. This test may be used for infants and young children to measure the amount of acid in their stool. Undigested and unabsorbed lactose ferments in the colon, creating lactic acid and other acids that can be detected in a stool sample.

What are the treatment options for lactose intolerance?
Lactose intolerance is relatively easy to treat. The amount of lactase enzyme that the body produces cannot be increased, but symptoms can be controlled through diet.

Many children and adults do not need to avoid lactose completely, but individuals differ in the amounts of lactose they can handle.

To reduce symptoms of lactose intolerance:

• Choose low-lactose dairy products such as buttermilk and aged cheeses (cheddar)
• Eat foods with active cultures such as yogurt
• Eat or drink dairy products with other foods to lessen symptoms
• Substitute fruit juice for some or all of the milk in recipes
• Avoid eating many high-lactose foods (such as milk and ice cream) at one time
• Choose dairy product substitutes such as Lactaid
  

Dairy products are a good source of calcium. Adults and children need calcium. Talk to your doctor about ways to get enough calcium without dairy. Foods other than dairy products that contain calcium include:

• Green vegetables such as broccoli, kale, bok choy (Chinese cabbage) and turnip greens
• Fish with edible bones such as canned salmon
• Alfalfa or soy sprouts
• Tofu soybeans, pinto beans, and navy beans
• Almonds
• Sesame seeds
• Molasses
• Calcium-fortified drinks such as orange juice, soy milk and rice milk
• Lactose-free milk

When to seek medical advice:
If you have signs and symptoms of lactose intolerance, talk to your doctor. Don't diagnose yourself. Your symptoms could be an indication of another illness. Your doctor can help determine if you have lactose intolerance or another condition.

Additional resources:
American Gastroenterological Association
www.gastro.org

American Dietetic Association
http://www.eatright.org